let me eat cake

cake

### section 1

# disable CPU mitigations, disable CPU sleep (C states), disable CPU throttling (frequency scaling)

# edit /boot/grub/grub.cfg
# mitigations=off intel_idle.max_cstate=0 processor.max_cstate=1

echo performance > /sys/devices/system/cpu/cpufreq/policy0/scaling_governor
echo performance > /sys/devices/system/cpu/cpufreq/policy1/scaling_governor

# you can verify the above were correctly disabled with "i7z" https://packages.ubuntu.com/i7z


### section 2

# disable / correctly configure NIC interrupt throttling / packet coalescing at the driver level (if necessary for your driver)

#rmmod r8169 ; rmmod r8168
#insmod r8168 use_dac=1 rx_copybreak=256 eee_enable=0 aspm=0 timer_count=0

#eqhmcow@OpenWrt:~$ cat /etc/modules.d/e1000e
#e1000e InterruptThrottleRate=0

# or after booting:
rmmod e1000e ; insmod e1000e InterruptThrottleRate=0


### section 3

# disable NIC offloading, configure NIC hardware buffers, etc

# also consider ethtool -C to disable coalescing if necessary for your driver
# high RX buffer; low TX buffer
# theory behind a high RX buffer: this gets packets into cake on our side quickly, to soak up
# and help mitigate other buffers that might be bloated
# also high RX reduces the chance we drop packets that we didn't want to drop
for i in eth0 eth1 ; do
  for j in rx tx sg tso ufo gso gro lro ntuple rxhash ; do
    /usr/sbin/ethtool -K $i $j off
  done
  /usr/sbin/ethtool -A $i autoneg off rx off tx off
  /usr/sbin/ethtool -G $i rx 4094 tx 66
  /usr/sbin/ethtool -G $i rx 4095 tx 65
  /usr/sbin/ethtool -G $i rx 4096 tx 64
done

sleep 5

service network restart

sleep 5


### section 4

# default: 0
echo 1 > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/net/eth0/napi_threaded
echo 1 > /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.0/net/eth1/napi_threaded

sleep 5

# IFF you use cake's "bandwidth" option, then "byte queue limits" don't matter much
# otherwise set the BQL max very low (3000 or less, down from the default of 1879048192)
echo 0 > /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.0/net/eth1/queues/tx-0/byte_queue_limits/limit_min
echo 0 > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/net/eth0/queues/tx-0/byte_queue_limits/limit_min
# default 1879048192
#echo 3000 > /sys/devices/pci0000:00/0000:00:1c.0/0000:02:00.0/net/eth1/queues/tx-0/byte_queue_limits/limit_max
#echo 3000 > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/net/eth0/queues/tx-0/byte_queue_limits/limit_max

# 64 default
echo 4 > /proc/sys/net/core/dev_weight

#    20000 default
echo 0 > /proc/sys/net/core/netdev_budget_usecs

#     300 default
echo 0 > /proc/sys/net/core/netdev_budget

#    1000 default
echo 1000000000 > /proc/sys/net/core/netdev_max_backlog


# set up cake

WAN=eth1
LAN=eth0

/usr/sbin/tc qdisc del dev $WAN root 2> /dev/null
/usr/sbin/tc qdisc del dev $LAN root 2> /dev/null

# in my testing, around 40mbit is the best that wifi can do w/o latency increasing

BANDWIDTH=46mbit
UPBANDWIDTH=20mbit
/usr/sbin/tc qdisc add dev $WAN handle 1: root cake besteffort bandwidth $UPBANDWIDTH internet nat egress ack-filter dual-srchost ethernet memlimit 134217728
/usr/sbin/tc qdisc add dev $LAN handle 1: root cake besteffort bandwidth $BANDWIDTH internet ingress dual-dsthost ethernet memlimit 134217728